As is tradition, Terra learns on the Saturday past her twelfth birthday that she is a Nature’s Spirit. It is her legacy to serve in the peaceful underground city of Concord. Learning she is named in a prophecy and being threatened by the leader of the death tribe...that part breaks tradition.

The Trepidus are the death janitors of the Underworld, responsible for delivering fatalities with a smile and cleaning up after themselves until Blanco, recent leader of the Trepidus, decides the day of reckoning for his species is coming. He begins organizing the creatures and leads them toward an uprising. The prophecy says there is one person who can stop him. Terra.

With Spirit of Security, Frank, protecting her, Terra attempts to complete her training and discover her Spirit talents. Together, they go on a rogue investigation to learn how to defeat Blanco. In the end, it comes down to a battle of the minds. The future of Concord is at stake. Will Blanco, the older, more experienced being win? Or will Terra, the young, new Spirit earn back the peace of the city?